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Quantum Fields and Strings Group Seminar
Lee–Yang Zeros and Dynamical Quantum Phases in Integrable Quantum Circuits
Lee–Yang Zeros and Dynamical Quantum Phases in Integrable Quantum Circuits
Organizers
Speaker
Yunfeng Jiang
Time
Thursday, March 19, 2026 2:30 PM - 4:00 PM
Venue
A7-302
Online
Zoom 388 528 9728
(BIMSA)
Abstract
Integrable quantum circuits form a novel class of quantum integrable models in which the dynamics is generated by unitary quantum gates. Among these, the integrable brickwork circuit serves as a paradigmatic example and can be solved exactly using integrability techniques such as the Bethe ansatz. A natural observable in such models is the correlation function of a string of spin operators. In the long-time limit, the zeros of these correlation functions condense onto curves in the complex plane, partitioning it into distinct regions. Each region corresponds to a different dynamical phase, characterized by qualitatively distinct asymptotic behavior of the correlation functions. We investigate a family of integrable brickwork circuits closely related to the XXZ spin chain. By tuning a parameter analogous to the anisotropy in the XXZ model, we observe a sharp transition in the condensation pattern of the Lee–Yang zeros, signaling a dynamical phase transition. In this talk, I will first introduce the integrable brickwork circuit and then present the method for exact computation of correlation functions. Finally, I will discuss the structure of Lee–Yang zeros and their implications for dynamical phase transitions.